Dynamic gel as artificial interphase layer for ultrahigh-rate and large-capacity lithium metal anode

Interweaved Nanofiber Anode Coating Based on Covalent Organic Frameworks for High-Performance Lithium-Metal Batteries

High-rate lithium-metal batteries call for unique interfacial structures of anode with interfacial compatibility, facilitated lithium insertion/extraction and dendrite suppression properties to meet the growing high-rate demand. Here, we develop an interweaved porous coating based on a kind of covalent organic framework (ODH─Cu3─COF) based helical nanofibers through the assembly of non-linear oxalyldihydrazide unit and rigid Cu3 unit. The interweaved helical nanofibers network with well-arranged polar groups (i.e., C═N, ─CO─NH─, and pyrazole groups) could serve as nuclei sites to achieve fast Li+ insertion/extraction and dendrite suppression in high-rate conditions. Benefiting from the advantages of interface design, the resultant ODH─Cu3─COF modified anode improves the Coulombic efficiency (97.5%, 120 cycles at 5 mA cm-2) and showcases a stable lifespan (1000 h at 2 mA cm-2 and 2 mAh cm-2) in symmetric cell. Moreover, the high-rate property of ODH─Cu3─COF@Li||LFP full cell presents an excellent cycling stability (900 cycles at 5 C) in commercial carbonate electrolyte. Theoretical calculations reveal that lithiophilic ODH─Cu3─COF has high Li affinity to reduce the nucleation barrier and achieve fast desolvation process in an interface to promote the lifespan of high-rate lithium-metal batteries.

Toward Zero-Excess Alkali Metal Batteries: Bridging Experimental and Computational Insights

This review introduces alkali metal (Li, Na, and K) anode-less and anode-free batteries and conveys a synopsis of the current challenges regarding anode-electrolyte interfaces. The review focuses on a critical analysis of the fundamental understanding of the (eletro)chemical and (electro)physical processes occurring at the anode, including metal nucleation and dendrite growth, the properties of liquid and solid electrolytes, and their roles in the metal stripping/deposition process and the formation of solid-electrolyte interphase, and the properties of separators and their role in inhibiting dendrite growth. Solutions to tackle the challenges for anode-less and anode-free batteries are discussed extensively in the aspects of the modifications of the anode substrate, novel electrolyte solutions and SEI structures, interface design, and novel separators/solid-state electrolytes to enable stable battery performances. To highlight the importance of bridging experimental and computational insights, experimental progress derived from a range of advanced characterization techniques is analyzed in combination with the advancement in multi-scale theory and computational modeling. Finally, outlooks are provided from both experimental and computational points of view for the exciting field of zero-excess alkali metal batteries.

Topological Li-SbF3@Cu Alloying Anode for High-Energy-Density Li Metal Batteries

The ultrathin Lithium (Li) alloying anode (≤ 50 µm) plays a key role in advancing rechargeable Li metal batteries into practical use, especially because of the insurmountable difficulties in developing pure Li anode. Herein, a thickness-controllable (≈5.5-30 µm) and topological Li-SbF3@Cu anode with the embedded dual Li-based (Li3Sb and Li-Cu) alloys and outmost LiF-rich layer is prepared for high-energy-density Li metal batteries under high Li utilization. Upon cycling, the surface LiF-rich layer together with inner lithiophilic Li3Sb sites and ferroconcrete-like Li-Cu skeletons, synergistically regulates the Li deposition/dissolution behaviors and Li/electrolyte interface evolution. The assembled Li-SbF3@Cu symmetric cell can cycle stably over 1200 h at 1 mA cm-2/1 mAh cm-2, and realize an ultrahigh discharge/charge depth of 53.6% at 2 mA cm-2/3 mAh cm-2. Moreover, a full cell with a high-Li-capacity LiCoO2 cathode (3.8 mAh cm-2) delivers an energy density of 394.5 Wh kg-1 with impressive cycling reversibility at a low negative/positive electrode capacity (N/P) ratio of 1.5. All the findings provide a rewarding avenue toward the industrial application of high-Li-utilization alloying anodes for practical high-energy-density Li metal batteries.

High energy electron beam irradiation on the electrolyte enables fast-charging of lithium metal batteries with long-term cycling stability

Electron beam (E-beam) irradiation serves as a pivotal tool within the realms of materials science, nanotechnology, and microelectronics. Its application is instrumental in altering the physical and chemical properties of materials, thereby enabling the exploration of material characteristics and fostering the advent of novel technological advancements. In this study, we irradiated the commercially available carbonate-based electrolyte LB-085 using a 10 MeV electron beam to examine the effects of electron beam (E-beam) irradiation on the electrolyte of lithium-metal batteries and explore the quantitative relationship between the absorbed radiation dose and battery's electrochemical performance. The applied absorbed radiation doses were 10, 25, and 50 kGy. Among these, the electrolyte irradiated with an absorbed radiation dose of 50 kGy effectively mitigated interfacial side reactions that occurred during the cycles of an electrode, securing a stable solid-state electrolyte interphase (SEI), which was characterized by a high ionic conductivity. This, in turn, facilitated rapid charging performance of the battery. The lithium metal full-cell assembled with LiNi0.91Co0.06Mn0.03O2 (NCM91) demonstrated superior capacity retention, exceeding 80% after 450 cycles at 4C rate (1C = 220 mA g-1, with charge times under 15 min) and also exceeding 80% after 600 cycles at 6C rate with an absorbed radiation dose of 50 kGy on the electrolyte. Thus, this research provides fresh perspectives for electrolyte optimization, focusing on enhancing the rapid charging performance of batteries.

In situ formation of ultrahigh molecular weight polymers in highly concentrated electrolytes and their physicochemical properties

We developed a facile one-pot method for fabricating physical gels consisting of ultrahigh molecular weight (UHMW) polymers and highly concentrated lithium salt electrolytes. We previously reported physical gels formed from the entanglement of UHMW polymers by radical polymerisation in aprotic ionic liquids. In this study, we found that the molecular weight of methacrylate polymers formed by radical polymerisation increased with the concentration of lithium salts in the organic solvents. Consequently, the synthesis of UHMW polymers with a high monomer conversion was achieved at very low initiator concentrations, leading to the formation of physical gels in highly concentrated electrolytes by the chain entanglement of UHMW polymers. The viscoelastic and mechanical properties of the UHMW gel electrolytes and their self-healing properties were investigated in detail.

In situ Polymerized Solid-State Electrolyte Enabling Inorganic-Organic Dual-Layered SEI Film for Stable Lithium Metal Batteries

In situ polymerization of cyclic ethers is a promising strategy to construct solid-state lithium (Li) metal batteries with high energy density and safety. However, their practical applications are plagued by the unsatisfactory electrochemical properties of polymer electrolytes and the unstable solid electrolyte interphase (SEI). Herein, organic perfluorodecanoic acid (PFDA) is proposed as a new initiator to polymerize 1,3-dioxolane electrolyte (PDOL), which enables the as-obtained PDOL electrolyte to deliver greatly enhanced ionic conductivity and broadened electrochemical window. Besides, the experimental data and theoretical calculations demonstrate a dual-layered SEI with PFDA-derived organic component on the top and LiF at the bottom constructed on the surface of Li metal, which can provide enough mechanical strength to suppress Li dendrite growth and high flexibility to accommodate volume fluctuations during the repeated cycling. As a result, the Li symmetric cells with PFDA-induced PDOL electrolyte (P-PDOL) can achieve a superior plating/stripping cycle for 1400 h at 0.3 mA cm-2. Additionally, the Li||P-PDOL||LiFePO4 (LFP) full cells maintain stable cycling over 300 times at 0.5 C. This work offers a potential strategy to simultaneously prepare high-performance PDOL electrolytes and stabilize the Li metal/PDOL interface, providing new research insights to advance solid-state Li metal batteries toward practical applications.

Facile Electrodeposition Method for Constructing Li2S as Artificial Solid Electrolyte Interphase for High-Performance Li Metal Anode

Designing current collectors and constructing efficient artificial solid electrolyte interphase (SEI) layers are promising strategies for achieving dendrite-free Li deposition and practical applications in Li metal batteries (LMBs). Electrodeposition is advantageous for large-scale production and allows the direct formation of current collectors without binders, making them immediately usable as electrodes. In this study, an adherent Cu2S thin-layer on Cu foil is synthesized through anodic electrodeposition from a Na2S solution in a one-step process, followed by the generation of Li2S layers as artificial SEI layers via a conversion reaction (3DLi2S-Cu foil). The Li2S layers move from the 3D Cu surface to the deposited Li surface, facilitating uniform and dense Li deposition. The 3DLi2S-Cu foil structure demonstrates stable cycling performance over 350 cycles in an asymmetric cell, with a capacity of 1 mAh cm-2 at 1 mA cm-2. Moreover, symmetric cells with 5 mAh cm-2 of deposited Li exhibit a stable cycle life for over 1200 h. When paired with commercial LiFePO4 (LFP), the full cells show substantially enhanced cyclability, regardless of the amount of deposited Li. This study provides new insights into the construction of artificial SEIs for facilitating commercial applications.

Controlled Interfacial Tailoring of Hierarchical Silicon Synergizes Charge Transport Enabling Stable and Fast Lithium Storage

Silicon is a promising anode material candidate but encounters volume change and capacity decay issues. Although diverse demonstrations in structural and interfacial engineering, the performance toward industrial applications remains to be improved. Herein, a controlled interfacial tailoring strategy is proposed for micro-nano hierarchically structured silicon. The resultant granules, consisting of randomly interconnected silicon debris modified by an electrically conductive carbon layer and a superionic sulfide conductor specifically in a controlled form (nanoparticles, coats, and matrices), attain distinctly different cyclic performances. As the carbon coating generally provides electron transfer paths for silicon, the introduced fast ion conductor exhibits a strong correlation with its configuration in facilitating ion transportation as well as improving the materials utilization and cyclic stability. Impressively, the granules encapsulated with a fast ion conductor layer show remarkably improved cycling performance and rate capability, attributable to a decent synergy of transmitting both electrons and lithium ions throughout the granule.

Multifunctional Ultrathin Ti3C2Tx MXene@CuCo2O4 /PE Separator for Ultra-High-Energy-Density and Large-Capacity Lithium-Sulfur Pouch Cells

The shuttling of lithium polysulfides (LiPSs), sluggish reaction kinetics, and uncontrolled lithium deposition/stripping remain the main challenges in lithium-sulfur batteries (LSBs), which are aggravated under practical working conditions, i.e., high sulfur loading and lean electrolyte in large-capacity pouch cells. This study introduces a Ti3C2Tx MXene@CuCo2O4 (MCC) composite on a polyethylene (PE) separator to construct an ultrathin MXene@CuCo2O4/PE (MCCP) film. The MCCP functional separator can deliver superior LiPSs adsorption/catalysis capabilities via the MCC composite and regulate the Li+ deposition through a conductive Ti3C2Tx MXene framework, enhancing redox kinetics and cycling lifetime. When paired with sulfur/carbon (S/C) cathode and lithium metal anode, the resultant 10 Ah-level pouch cell with the ultrathin MCCP separator achieves an energy density of 417 Wh kg-1 based on the whole cell and a stable running of 100 cycles under practical operation conditions (cathode loading = 10.0 mg cm-2, negative/positive areal capacity ratio (N/P ratio) = 2, and electrolyte/sulfur weight ratio (E/S ratio) = 2.6 µL mg-1). Furthermore, through a systematic evaluation of the as-prepared Li-S pouch cell, the study unveils the operational and failure mechanisms of LSBs under practical conditions. The achievement of ultrahigh energy density in such a large-capacity lithium-sulfur pouch cell will accelerate the commercialization of LSBs.

Dynamic Imine Chemistry Enables Paintable Biogel Electrolytes to Shield On-Body Zinc-Ion Batteries from Interfacial Interference

On-body batteries with hydrogel electrolytes are a pivotal enabling technology to drive bioelectronics for healthcare and sports, yet they are prone to failure due to dynamic interfacial interference, accompanied by e-waste production. Here, dynamic imine chemistry is proposed to design on-electrode paintable biogel electrolytes that feature temperature-controlled reversible phase transition (gelling within 1.5 min) and ultrafast self-healing capability (6 s), establishing a dynamically self-adaptive interface on cyclically deforming electrodes for shielding on-body Zn-ion batteries from interfacial interference. Consequently, the deformed Zn anode shows an exceptional cycling stability of 400 h regardless of the bending radius, and the as-assembled Zn-I2 battery delivers sufficient durability to endure 5000 deformation cycles, together extending to 1300 h and 15 000 deformation cycles via dynamically restarting the interfacial electric field, respectively. Also, the features of recyclability, biodegradation, and biocompatibility make the proposed on-body Zn-I2 batteries appealing in terms of sustainability and biosafety, enabling their successful power supply of heart rate monitors in sports. This work demonstrates the promise of dynamic biogel chemistry for green and biorelated energy-storage systems.

An In Situ Generated Organic/Inorganic Hybrid SEI Layer Enables Li Metal Anodes with Dendrite Suppression Ability, High-Rate Capability, and Long-Life Stability

High-quality solid electrolyte interphase (SEI) layers can effectively suppress the growth of Li dendrites and improve the cycling stability of lithium metal batteries. Herein, 1-(6-bromohexanoyl)-3-butylurea is used to construct an organic/inorganic hybrid (designated as LiBr-HBU) SEI layer that features a uniform and compact structure. The LiBr-HBU SEI layer exhibits superior electrolyte wettability and air stability as well as strong attachment to Li foils. The LiBr-HBU SEI layer achieves a Li+ conductivity of 2.75 × 10-4 S cm-1, which is ≈50-fold higher than the value measured for a native SEI layer. A Li//Li symmetric cell containing the LiBr-HBU SEI layer exhibits markedly improved cyclability when compared with the cell containing a native SEI layer, especially at a high current density (e.g., cycling life up to 1333 h at 15 mA cm-2). The LiBr-HBU SEI layer also improves the performance of lithium-sulfur cells, particularly the rate capability (548 mAh g-1 at 10 C) and cycling stability (513 mAh g-1 at 0.5 C after 500 cycles). The methodology described can be extended to the commercial processing of Li metal anodes as the artificial SEI layer also protects Li metal against corrosion.

In Situ Inorganic/Organic Protective Layer on Carbon Paper as Advanced Current Collector for Robust Li Metal Anode

Lithium (Li) metal is regarded as the most promising anode for next-generation batteries with high energy density. However, the uncontrolled dendrite growth and infinite volume expansion during cycling seriously hinder the application of Li metal batteries (LMBs). Herein, an inorganic/organic protective layer (labeled as BPH), composed of in situ formed inorganic constituents and PVDF-HFP, is designed on the 3D carbon paper (CP) surface by hot-dipping method. The BPH layer can effectively improve the mechanical strength and ionic conductivity of the SEI layer, which is beneficial to expedite the Li-ion transfer of the entire framework and achieve stable Li plating/stripping behavior. As a result, the modified 3D CP (BPH-CP) exhibits an ultrahigh average Coulombic efficiency (CE) of ≈99.7% over 400 cycles. Further, the Li||LiFePO4 (LFP) cell exhibits an extremely long-term cycle life of over 3000 cycles at 5 C. Importantly, the full cell with high mass loading LiFePO4 (20 mg cm-2) or LiNi0.8Co0.1Mn0.1O2 (NCM, 16 mg cm-2) cathode exhibits stable cycling for 100 or 150 cycles at 0.5 C with high-capacity retention of 86.5% or 82.0% even at extremely low N/P ratio of 0.88 or 0.94. believe that this work enlightens a simple and effective strategy for the application of high-energy-density and high-rate-C LMBs.

Development and Optimization of Thin-Lithium-Metal Anodes with a Lithium Lanthanum Titanate Stabilization Coating for Enhancement of Lithium-Sulfur Battery Performance

Lithium-ion batteries are dominating high-energy-density energy storage for 30 years. However, their development approaches theoretical limits, spurring the development of lithium-sulfur cells that achieve high energy densities through reversible electrochemical conversion reactions. Nevertheless, the commercialization of lithium-sulfur cells is hindered by practical challenges associated primarily with the use of thick-lithium anodes, low-loading sulfur cathodes, and high electrolyte-to-sulfur ratios, which prevent realization of the cells' full potential in terms of electrochemical and material performance. To solve these extrinsic and intrinsic problems, the effect of lithium-metal thickness on the electrochemical behavior of lithium-sulfur cells with high-loading sulfur cathodes in lean-electrolyte configurations is investigated. Specifically, lithium lanthanum titanate (LLTO), a solid electrolyte, is utilized to form an ionically/electronically conductive coating to stabilize lithium-metal anodes, thereby enhancing their lithium-ion pathways and interfacial charge transfer. Electrochemical analyses reveal that an LLTO coating significantly reduces excessive reactions between lithium metal and an electrolyte, thereby minimizing lithium consumption and electrolyte depletion. Further, LLTO-stabilized lithium anodes improve lithium-sulfur cell performance, and most importantly, allow the fabrication of thin-lithium, high-loading-sulfur cells that open a pathway toward high-energy-density batteries.

Versatile Biopolymers for Advanced Lithium and Zinc Metal Batteries

Lithium (Li) and zinc (Zn) metals are emerging as promising anode materials for next-generation rechargeable metal batteries due to their excellent electronic conductivity and high theoretical capacities. However, issues such as uneven metal ion deposition and uncontrolled dendrite growth result in poor electrochemical stability, limited cycle life, and rapid capacity decay. Biopolymers, recognized for their abundance, cost-effectiveness, biodegradability, tunable structures, and adjustable properties, offer a compelling solution to these challenges. This review systematically and comprehensively examines biopolymers and their protective mechanisms for Li and Zn metal anodes. It begins with an overview of biopolymers, detailing key types, their structures, and properties. The review then explores recent advancements in the application of biopolymers as artificial solid electrolyte interphases, electrolyte additives, separators, and solid-state electrolytes, emphasizing how their structural properties enhance protection mechanisms and improve electrochemical performance. Finally, perspectives on current challenges and future research directions in this evolving field are provided.

An Mn-Enriched Interfacial Layer for Reversible Aqueous Mn Metal Batteries

Aqueous manganese metal batteries have emerged as promising candidates for stationary storage due to their natural abundance, safety, and high energy density. However, the high chemical reactivity and sluggish migration kinetics of the Mn metal anode induce a severe hydrogen evolution reaction (HER) and dendrite formation, respectively. The situation deteriorates in the low-concentration electrolyte especially. Here, we propose a novel approach to construct an Mn-enriched interfacial layer (Mn@MIL) on the Mn metal anode surface to address these challenges simultaneously. The Mn@MIL acts as a physical barrier to not only suppress HER but also accelerate the Mn2+ diffusion kinetics through the Mn2+ saturated interfacial layer to inhibit dendrite growth. Therefore, in the low-concentration electrolyte (1 M MnCl2), the Mn||Mn symmetric cells and Mn||V2O5 full cells with high mass loading demonstrate promising cycling stability with minimal polarization and parasitic reactions, making them more suitable for practical applications in a smart grid.

In Situ-Constructed Multifunctional Composite Anode with Ultralong-Life Toward Advanced Lithium-Metal Batteries

Metallic lithium is the most competitive anode material for next-generation high-energy batteries. Nevertheless, the extensive volume expansion and uncontrolled Li dendrite growth of lithium metal not only cause potential safety hazards but also lead to low Coulombic efficiency and inferior cycling lifespan for Li metal batteries. Herein, a multifunctional dendrite-free composite anode (Li/SnS2) is proposed through an in situ melt-infusion strategy. In this configuration, the 3D cross-linked porous Li2S/Li22Sn5 framework facilitates the rapid penetration of electrolytes and accommodates the volume expansion during the repeated Li-plating process. Meanwhile, the lithiophilic Li2S phases with a low Li+ transport barrier ensure preferential Li deposition, effectively avoiding uneven electron distribution. Moreover, the Li22Sn5 electron conductors with appropriate Li+ bonding ability guarantee rapid charge transport and mass transfer. Most importantly, the steady multifunctional skeleton with sufficient inner interfaces (Li2S/Li22Sn5) in the whole electrode, not only realizes the redistribution of the localized free electron, contributing to the decomposition of Li clusters, but also induces a planar deposition model, thus restraining the generation of Li dendrites. Consequently, an unprecedented cyclability of over 6 500 h under an ultrahigh areal capacity of 10 mAh cm-2 and a current rate of 20 mA cm-2 is achieved for the prepared Li2S/Li22Sn5 composite anode. Moreover, the assembled Li/SnS2||LiFePO4 (LFP) pouch full-cells also demonstrate remarkable rate capability and a convincing cycling lifespan of more than 2 000 cycles at 2 C.

Steric Hindrance Engineering to Modulate the Closed Pores Formation of Polymer-Derived Hard Carbon for High-Performance Sodium-Ion Batteries

The closed pores play a critical role in improving the sodium storage capacity of hard carbon (HC) anode, however, their formation mechanism as well as the efficient modulation strategy at molecular level in the polymer-derived HCs is still lacking. In this work, the steric hindrance effect has been proposed to create closed pores in the polymer-derived HCs for the first time through grafting the aromatic rings within and between the main chains in the precursor. The experimental data and theoretical calculation demonstrate that steric-hindrance effect from the aromatic ring side group can increase backbone rigidity and the internal free volumes in the polymer precursor, which can prevent the over graphitization and facilitate the formation of closed pores during the carbonization process. As a result, the as-prepared HC anode exhibits a remarkably enhanced discharge capacity of 340.3 mAh/g at 0.1 C, improved rate performance (210.7 mAh/g at 5 C) as well as boosted cycling stability (86.4 % over 1000 cycles at 2 C). This work provides a new insight into the formation mechanisms of closed pores via steric hindrance engineering, which can shed light on the development of high-performance polymer-derived HC anode for sodium-ion batteries.

LiF-Rich Solid Electrolyte Interphase Formation by Establishing Sacrificial Layer on the Separator

The formation of a stable solid electrolyte interphase (SEI) layer is crucial for enhancing the safety and lifespan of Li metal batteries. Fundamentally, a homogeneous Li+ behavior by controlling the chemical reaction at the anode/electrolyte interface is the key to establishing a stable SEI layer. However, due to the highly reactive nature of Li metal anodes (LMAs), controlling the movement of Li+ at the anode/electrolyte interface remains challenging. Here, an advanced approach is proposed for coating a sacrificial layer called fluorinated self-assembled monolayer (FSL) on a boehmite-coated polyethylene (BPE) separator to form a stable SEI layer. By leveraging the strong affinity between the fluorine functional group and Li+, the rapid formation of a LiF-rich SEI layer in the cell production and early cycling stage is facilitated. This initial stable SEI formation promotes the subsequent homogeneous Li+ flux, thereby improving the LMA stability and yielding an enhanced battery lifespan. Further, the mechanism behind the stable SEI layer generation by controlling the Li+ dynamics through the FSL-treated BPE separator is comprehensively verified. Overall, this research offers significant contributions to the energy storage field by addressing challenges associated with LMAs, thus highlighting the importance of interfacial control in achieving a stable SEI layer.

The Progress of Polymer Composites Protecting Safe Li Metal Batteries: Solid-/Quasi-Solid Electrolytes and Electrolyte Additives

The impressive theoretical capacity and low electrode potential render Li metal anodes the most promising candidate for next-generation Li-based batteries. However, uncontrolled growth of Li dendrites and associated parasitic reactions have impeded their cycling stability and raised safety concerns regarding future commercialization. The uncontrolled growth of Li dendrites and associated parasitic reactions, however, pose challenges to the cycling stability and safety concerns for future commercialization. To tackle these challenges and enhance safety, a range of polymers have demonstrated promising potential owing to their distinctive electrochemical, physical, and mechanical properties. This review provides a comprehensive discussion on the utilization of polymers in rechargeable Li-metal batteries, encompassing solid polymer electrolytes, quasi-solid electrolytes, and electrolyte polymer additives. Furthermore, it conducts an analysis of the benefits and challenges associated with employing polymers in various applications. Lastly, this review puts forward future development directions and proposes potential strategies for integrating polymers into Li metal anodes.

Super-Ionic Conductor Soft Filler Promotes Li+ Transport in Integrated Cathode-Electrolyte for Solid-State Battery at Room Temperature

Composite polymer solid electrolytes (CPEs), possessing good rigid flexible, are expected to be used in solid-state lithium-metal batteries. The integration of fillers into polymer matrices emerges as a dominant strategy to improve Li+ transport and form a Li+-conducting electrode-electrolyte interface. However, challenges arise as traditional fillers: 1) inorganic fillers, characterized by high interfacial energy, induce agglomeration; 2) organic fillers, with elevated crystallinity, impede intrinsic ionic conductivity, both severely hindering Li+ migration. Here, a concept of super-ionic conductor soft filler, utilizing a Li+ conductivity nanocellulose (Li-NC) as a model, is introduced which exhibits super-ionic conductivity. Li-NC anchors anions, and enhances Li+ transport speed, and assists in the integration of cathode-electrolyte electrodes for room temperature solid-state batteries. The tough dual-channel Li+ transport electrolyte (TDCT) with Li-NC and polyvinylidene fluoride (PVDF) demonstrates a high Li+ transfer number (0.79) due to the synergistic coordination mechanism in Li+ transport. Integrated electrodes' design enables stable performance in LiNi0.5Co0.2Mn0.3O2|Li cells, with 720 cycles at 0.5 C, and 88.8% capacity retention. Furthermore, the lifespan of Li|TDCT|Li cells over 4000 h and Li-rich Li1.2Ni0.13Co0.13Mn0.54O2|Li cells exhibits excellent performance, proving the practical application potential of soft filler for high energy density solid-state lithium-metal batteries at room temperature.

Regenerated Ni-Doped LiCoO2 from Spent Lithium-Ion Batteries as a Stable Cathode at 4.5 V

In the context of the increasing number of spent lithium-ion batteries, it is urgent to explore cathode regeneration and upcycling solutions to reduce environmental pollution, promote resource reuse, and meet the demand for high-energy cathode materials. Here, a closed-loop recycling method is introduced, which not only reclaims cobalt and lithium elements from spent lithium-ion batteries but also converts them into high-voltage LiCoO2 (LCO) materials. This approach involved pretreatment, chlorination roasting, water leaching, and ion doping to regenerate nickel-doped LCO (Ni-RLCO) materials. The doping of nickel effectively enhances the electrochemical stability of the LCO cathode at 4.5 V. The Ni-RLCO cathode exhibited a high discharge specific capacity of 185.28 mAh/g at a rate of 0.5 C with a capacity retention of 86.3% after 50 cycles and excellent rate capacity of 156.21 mAh/g at 2 C. This work offers a approach in significance for upcycling spent LCO into high-energy-density batteries with long-term cycling stability under high voltage.

Sustained Release-Driven Interface Engineering Enables Fast Charging Lithium Metal Batteries

LiNO3 has attracted intensive attention as a promising electrolyte additive to regulate Li deposition behavior as it can form favorable Li3N, LiNxOy species to improve the interfacial stability. However, the inferior solubility in carbonate-based electrolyte restricts its application in high-voltage Li metal batteries. Herein, an artificial composite layer (referred to as PML) composed of LiNO3 and PMMA is rationally designed on Li surface. The PML layer serves as a reservoir for LiNO3 release gradually to the electrolyte during cycling, guaranteeing the stability of SEI layer for uniform Li deposition. The PMMA matrix not only links the nitrogen-containing species for uniform ionic conductivity but also can be coordinated with Li for rapid Li ions migration, resulting in homogenous Li-ion flux and dendrite-free morphology. As a result, stable and dendrite-free plating/stripping behaviors of Li metal anodes are achieved even at an ultrahigh current density of 20 mA cm-2 (>570 h) and large areal capacity of 10 mAh cm-2 (>1200 h). Moreover, the Li||LiFePO4 full cell using PML-Li anode undergoes stable cycling for 2000 cycles with high-capacity retention of 94.8%. This facile strategy will widen the potential application of LiNO3 in carbonate-based electrolyte for practical LMBs.

Cation-polymerized artificial SEI layer modified Li metal applied in soft-matter polymer electrolyte

Li metal batteries with polymer electrolyte are of great interest for next-generation batteries for high safety and high energy density. However, uneven deposition on the lithium metal surface can greatly affect battery life. Therefore, surface modification on the Li metal become necessary to achieve good performance. Herein, an artificial solid electrolyte interface (SEI) modified lithium metal anode is prepared using cation-polymerization process, as triggered by PF5generated from CsPF6. As a result, the polarization voltage of Li||Li symmetric battery assembled with artificial SEI-modified Li metal anode was stable with a small over-potential of 25 mV after 3000 h at current density of 1.5 mA cm-2. Electrochemical performance of Li||NCM 622 (LiNi0.6Co0.2Mn0.2O2) full cell with soft-matter polymer electrolyte is significantly improved than bare Li-metal, the capacity retention is 75% after 120 cycles with N/P = 3:1 at a cut-off voltage of 4.3 V. Our work has shed lights on the commercialization of Li metal battery with polymer electrolyte.

A Triply-Periodic-Minimal-Surface Structured Interphase based on Fluorinated Polymers Strengthening High-energy Lithium Metal Batteries

The challenge of constructing a mechanically robust yet lightweight artificial solid-electrolyte interphase layer on lithium (Li) anodes highlights a trade-off between high battery safety and high energy density. Inspired by the intricate microstructure of the white sea urchin, we first develop a polyvinyl fluoride-hexafluoropropylene (PVDF-HFP) interfacial layer with a triple periodic minimal surface structure (TPMS) that could offer maximal modulus with minimal weight. This design endows high mechanical strength to an ordered porous structure, effectively reduces local current density, polarization, and internal resistance, and stabilizes the anode interface. At a low N/P ratio of ~3, using LiFePO4 as the cathode, Li anodes protected by TPMS-structured PVDF-HFP achieve an extremely low capacity-fading-rate of approximately 0.002 % per cycle over 200 cycles at 1 C, with an average discharge capacity of 142 mAh g-1. Meanwhile, the TPMS porous structure saves 50 wt % of the interfacial layer mass, thereby enhancing the energy density of the battery. The TPMS structure is conducive to large-scale additive manufacturing, which will provide a reference for the future development of lightweight, high-energy-density secondary batteries.

Achieving Stable Lithium Anodes through Leveraging Inevitable Stress Variations via Adaptive Piezoelectric Effect

Unleashing the potential of lithium-metal anodes in practical applications is hindered by the inherent stress-related challenges arising from their limitless volume expansion, leading to mechanical failures such as electrode cracking, solid electrolyte interphase damage, and dendritic growth. Despite the various protective strategies to "combat" stress in lithium-metal anodes, they fail to address the intrinsic issue fundamentally. Here, a unique strategy is proposed that leverages the stress generated during the battery cycling via the piezoelectric effect, transforming to the adaptive built-in electric field to accelerate lithium-ion migration, homogenize the lithium deposition, and alleviate the stress concentration. The mechanism of the piezoelectric effect in modulating electro-chemomechanical field evolution is further validated and decoupled through finite element method simulations. Inspired by this strategy, a high sensitivity, fast responsive, and strength adaptability polymer piezoelectric is used to demonstrate the feasibility and the corresponding protected lithium-metal anode shows cycling stability over 6000 h under a current density of 10 mA cm-2 and extending life in a variety of coin and pouch cell systems. This work effectively tackles the stress-related issues and decoupling the electro-chemomechanical field evolution also contributes to developing more stable lithium anodes for future research.

Bipolar Polymeric Protective Layer for Dendrite-Free and Corrosion-Resistant Lithium Metal Anode in Ethylene Carbonate Electrolyte

The unstable interface between Li metal and ethylene carbonate (EC)-based electrolytes triggers continuous side reactions and uncontrolled dendrite growth, significantly impacting the lifespan of Li metal batteries (LMBs). Herein, a bipolar polymeric protective layer (BPPL) is developed using cyanoethyl (-CH2CH2C≡N) and hydroxyl (-OH) polar groups, aiming to prevent EC-induced corrosion and facilitating rapid, uniform Li+ ion transport. Hydrogen-bonding interactions between -OH and EC facilitates the Li+ desolvation process and effectively traps free EC molecules, thereby eliminating parasitic reactions. Meanwhile, the -CH2CH2C≡N group anchors TFSI- anions through ion-dipole interactions, enhancing Li+ transport and eliminating concentration polarization, ultimately suppressing the growth of Li dendrite. This BPPL enabling Li|Li cell stable cycling over 750 cycles at 10 mA cm-2 for 2 mAh cm-2. The Li|LiNi0.8Mn0.1Co0.1O2 and Li|LiFePO4 full cells display superior electrochemical performance. The BPPL provides a practical strategy to enhanced stability and performance in LMBs application.

Fast-charging anodes for lithium ion batteries: progress and challenges

Slow charging speed has been a serious constraint to the promotion of electric vehicles (EVs), and therefore the development of advanced lithium-ion batteries (LIBs) with fast-charging capability has become an urgent task. Thanks to its low price and excellent overall electrochemical performance, graphite has dominated the anode market for the past 30 years. However, it is difficult to meet the development needs of fast-charging batteries using graphite anodes due to their fast capacity degradation and safety hazards under high-current charging processes. This feature article describes the failure mechanism of graphite anodes under fast charging, and then summarizes the basic principles, current research progress, advanced strategies and challenges of fast-charging anodes represented by graphite, lithium titanate (Li4Ti5O12) and niobium-based oxides. Moreover, we look forward to the development prospects of fast-charging anodes and provide some guidance for future research in the field of fast-charging batteries.

Enhanced Electron Delocalization within Coherent Nano-Heterocrystal Ensembles for Optimizing Polysulfide Conversion in High-Energy-Density Li-S Batteries

Commercialization of high energy density Lithium-Sulfur (Li-S) batteries is impeded by challenges such as polysulfide shuttling, sluggish reaction kinetics, and limited Li+ transport. Herein, a jigsaw-inspired catalyst design strategy that involves in situ assembly of coherent nano-heterocrystal ensembles (CNEs) to stabilize high-activity crystal facets, enhance electron delocalization, and reduce associated energy barriers is proposed. On the catalyst surface, the stabilized high-activity facets induce polysulfide aggregation. Simultaneously, the surrounded surface facets with enhanced activity promote Li2 S deposition and Li+ diffusion, synergistically facilitating continuous and efficient sulfur redox. Experimental and DFT computations results reveal that the dual-component hetero-facet design alters the coordination of Nb atoms, enabling the redistribution of 3D orbital electrons at the Nb center and promoting d-p hybridization with sulfur. The CNE, based on energy level gradient and lattice matching, endows maximum electron transfer to catalysts and establishes smooth pathways for ion diffusion. Encouragingly, the NbN-NbC-based pouch battery delivers a Weight energy density of 357 Wh kg-1 , thereby demonstrating the practical application value of CNEs. This work unveils a novel paradigm for designing high-performance catalysts, which has the potential to shape future research on electrocatalysts for energy storage applications.

Recycled Graphite from Spent Lithium-Ion Batteries as a Conductive Framework Directly Applied in Red Phosphorus-Based Anodes

The recycling of spent graphite from waste lithium-ion batteries (LIBs) holds great importance in terms of environmental protection and conservation of natural resources. In this study, a simple two-step method involving heat treatment and solution washing was employed to recycle spent graphite. Subsequently, the recycled graphite was milled with red phosphorus to create a carbon/red phosphorus composite that served as an anode material for the new LIBs, aiming to address the low capacity issue. In a half-cell configuration, the carbon/red phosphorus composite exhibited remarkable cycling stability, maintaining a capacity of 721.7 mAh g-1 after 500 cycles at 0.2 A g-1, and demonstrated an excellent rate performance with a capacity of 276.2 mAh g-1 at 3 A g-1. The improved performance can be attributed to the structure of the composite, where the red phosphorus particles are covered by the carbon layer. This composite outperformed pure recycled graphite, highlighting its potential in enhancing the electrochemical properties of LIBs. Furthermore, when the carbon/red phosphorus composite was assembled into a full-cell configuration with LiCoO2 as the cathode material, it displayed a stable electrochemical performance, further validating its practical applicability. This work presents a promising and green strategy for recycling spent graphite and using it in the production of new batteries. The findings offer a high potential for commercialization, contributing to the advancement of sustainable and ecofriendly energy storage technologies.

Organic Nitrate Additive for High-Rate and Large-Capacity Lithium Metal Anode in Carbonate Electrolyte

Lithium nitrate has been widely used to improve the interfacial stability of Li metal anode in ether electrolyte. However, the low solubility limits its application in carbonate electrolytes for high-voltage Li metal batteries. Herein, nitrated polycaprolactone (PCL-ONO2 ), which is prepared via the acylation of polycaprolactone diol (PCL-diol) followed by the grafting of nitrate group, has been proposed as an electrolyte additive to introduce high-concentration NO3 - into carbonate electrolytes for the first time. The theoretical calculations and X-ray photoelectron spectroscopy depth profiling demonstrate that the PCL-ONO2 additive preferentially reacts with Li metal and in situ constructs a stable dual-layered solid electrolyte interphase film, presenting an inner nitride-rich layer and an outer flexible PCL-based layer on the surface of Li metal anode. As a result, the Li metal anode delivers an impressive long-term cycling performance over 1400 h at an elevated area capacity of 10.0 mAh cm-2 and an ultrahigh current density of 10.0 mA cm-2 in the Li symmetrical cells. Moreover, the PCL-ONO2 additive enables the full cells constructed by coupling high-loading LiFePO4 (20.0 mg cm-2 ) or LiNi0.5 Co0.2 Mn0.3 (16.5 mg cm-2 ) cathode and thin Li metal anode (≈50 µm) to demonstrate greatly improved cycling stability and rate capability.